1. Field of the Invention
The present invention is in the field of dry etching of contact holes having beveled sidewalls and insulating layers composed of SiO.sub.2, the layers being employed as intermediate oxide layers in the manufacture of large scale integrated semiconductor circuits. The etching is carried out in a plasma containing a fluorine-containing etchant.
2. Description of the Prior Art
The steps between the various wiring levels consisting, for example, of polysilicon levels and aluminum interconnect levels which occur in very large scale integration technology require a leveling of the intermediate oxide which possesses good flow properties at low temperatures in order to provide a successful edge coverage at the succeeding steps. A phosphorusdoped or boron-doped silica glass meet this requirement very well. Contact holes which also must meet the demands of the aluminum edge coverage must be etched in the layers referred to as the intermediate oxide layers.